Power meter suggestions for T47bb bike

[kilka]

Xcadey powermeter seems to fit any t47 frame due to it's shape. It's central hole is only 3 mm deep and goes back 1mm to only 2 mm resulting. So as t47 adds 1 mm of it's external width, you'll have to place only one 1mm o-ring in worst case.

[sendmeurbrokenbikes]

Did you have to recalibrate the PM and if you did, was it difficult to do so?

Zrace+Magene powermeter fits t47 because of usage of plastic o-ring on powermeter's side and a special adapting ring on the other side. Resulting q-factor is something like 160mm on my frame and the powermeter has a lot of clearance to the frame.
I tried the same powermeter on my Senicx GR-3 cranks and it did not fitted my frame, Magene makes the central hole too deep.

[Takiyaki]

This is probably not going to be a popular opinion on this forum, but I would buy a used Quarq.  I have had two Chinese power meters, one stopped reading cadence (no power without cadence) and the other broke during a rainy 600k.  The Magene seems to have good reviews and seems like an overall solid product, but I have 3 Quarqs, and I purchased each one used for less than the price of a new Magene.  Between my Quarqs, I have over 20,000 miles and have had zero issues.  2 of them are currently on T47x85.5 bikes-- no issues there either.

My general policy is go Chinese for everything non-electronic/shifting related. I dont know how many miles I put on my Quarq but it has also been bulletproof.